Frictionless vertical suspension mechanism for prosthetic feet

ABSTRACT

A vertical suspension system for a prosthetic foot includes a first member operatively coupleable to an amputee&#39;s residual leg. The suspension system can also include a second member coupleable to a prosthetic foot. One or more upper leaf springs and one or more lower leaf springs extend between and are attached to the first and second members such that at least one of the ends of each leaf spring is rotationally fixed to the first or second members, where the upper an lower leaf springs are spaced apart from each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/626567, entitled “FRICTIONLESS VERTICALSUSPENSION MECHANISM FOR PROSTHETIC FEET” and filed Sep. 25, 2012, whichclaims priority benefit of U.S. Provisional Application No. 61/539,207,filed Sep. 26, 2011, the entirety of each of which is herebyincorporated by reference herein.

BACKGROUND

Field

The present application relates in certain embodiments to prostheticdevices. In particular, the present application in certain embodimentsrelates to a frictionless vertical suspension mechanism for a prostheticfoot.

Description of the Related Art

Prosthetic feet of different designs are well known in the art. Thevarious conventional designs have sought to solve various limitationsassociated with prosthetic feet.

Some prosthetic foot designs employ shock absorbing members (e.g., anklemembers). However, such shock absorbing members tend to be relativelyheavy and/or bulky. A common problem observed in prosthetic feet aimingfor high travel suspension is that when in mid-stance, the bodyweight issupported by both the toe and the heel, but at heel strike or toe-offthe weight is only supported by the respective part of the prostheticfoot. Therefore, the foot will be significantly stiffer at mid-stancethan at heel strike or toe-off. This can cause an “obstacle” likefeeling in the mid-stance of the rollover of the foot. Existingprosthetic feet with vertical suspension shock absorbers are also heavywith relatively high energy losses from, for example, the foot hittingthe ground and friction within the suspension system, and are thereforearguably not well suited for high active use, such as running.

Accordingly, there is a need for an improved shock absorbing member fora prosthetic foot that is lightweight and provides frictionless verticalsuspension regardless of the direction of the force on the prostheticfoot, and a need for a prosthetic foot incorporating the improved shockabsorbing member that has rollover characteristics fit for everyday useand that encourages highly active use (e.g., running) through itssuspension, energy return and light weight.

SUMMARY

In accordance with one embodiment, a lightweight, low energy loss,vertical suspension system for prosthetic feet is provided. The verticalsuspension system enables rollover characteristics between heel strikeand toe-off of a prosthetic foot that are fit for everyday use and atthe same time encourage highly active users (e.g., in running) throughits suspension, energy return and light weight. The substantiallyfrictionless nature of the vertical suspension system results insubstantially greater energy return than prior art alternativesuspension systems. As a result, the vertical suspension system iswell-suited for physically demanding activities such as running.

In accordance with another embodiment, a vertical suspension system fora prosthetic foot is provided. The suspension system comprises a firstmember having an upper coupling location and a lower coupling locationwherein the first member is adapted to be operatively coupled to anamputee's residual leg. The suspension system also comprises a secondmember having an upper coupling location and a lower coupling locationwherein the second member is adapted to be coupled to the prostheticfoot. At least one upper leaf spring having a first end portion and asecond end portion located on opposite ends of the upper leaf spring iscoupled to the first member's upper coupling location and to the secondmember's upper coupling location. At least one of the upper leafspring's first end portion and second end portion is rotationally fixedto at least one of the first member and the second member. At least onelower leaf spring having a first end portion and a second end portionlocated on opposite ends of the lower leaf spring is coupled to thefirst member's lower coupling location and to the second member's lowercoupling location. At least one of the lower leaf spring's first endportion and second end portion is rotationally fixed to at least one ofthe first member and the second member.

In accordance with another embodiment, a prosthetic foot is provided.The prosthetic foot comprises a foot plate extending from a generallyvertical proximal portion to a generally horizontal distal portion, thefoot plate curving downwardly and forwardly between the proximal anddistal portions. The prosthetic foot also comprises an adapter operablycoupleable to the proximal portion of the prosthetic foot and disposedforwardly of said proximal portion, the adapter operably coupleable to aprosthetic socket. The prosthetic foot further comprises a plurality ofparallel leaf springs that operably interconnect the adapter and theproximal portion of the prosthetic foot, the leaf springs spaced apartfrom each other and extending generally horizontally between the adapterand the proximal portion of the prosthetic foot.

In accordance with still another embodiment, a vertical suspensionsystem is provided. The suspension system comprises a first memberhaving an upper coupling location and a lower coupling location, and asecond member having an upper coupling location and a lower couplinglocation wherein the second member is configured to be fixedly coupledto a support component, the first member being movable relative to thesecond member. The suspension system also comprises at least one upperleaf spring having a first end portion and a second end portion locatedon opposite ends of the upper leaf spring, wherein the upper leaf springis coupled to the first member's upper coupling location and to thesecond member's upper coupling location. At least one of the upper leafspring's first end portion and second end portion is rotationally fixedto at least one of the first member and the second member. Thesuspension system also comprises at least one lower leaf spring having afirst end portion and a second end portion that are located on oppositeends of the lower leaf spring, wherein the lower leaf spring is coupledto the first member's lower coupling location and to the second member'slower coupling location. At least one of the lower leaf spring's firstend portion and second end portion is rotationally fixed to at least oneof the first member and the second member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic perspective front view of a conventionalprosthetic foot.

FIG. 1B is a schematic side view of a prosthetic foot including a shockmodule.

FIG. 2 is a schematic perspective side view of one embodiment of africtionless vertical suspension member coupled to the prosthetic footof FIG. 1.

FIG. 3 is a schematic perspective rear view of another embodiment of africtionless vertical suspension member coupled to the prosthetic footof FIG. 1.

FIG. 4 is a schematic perspective front view of the frictionlessvertical suspension member of FIG. 3 coupled to the prosthetic foot ofFIG. 1.

FIG. 5 is a schematic perspective side view of the frictionless verticalsuspension member of FIG. 3 coupled to the prosthetic foot of FIG. 1.

FIG. 6A is a schematic partial perspective rear view of one embodimentof a frictionless vertical suspension member portion coupled to aprosthetic foot.

FIG. 6B is a schematic partial rear view of the frictionless verticalsuspension member portion coupled to the prosthetic foot of FIG. 6A.

FIG. 6C is a schematic perspective front view of the prosthetic foot ofFIG. 6A.

FIG. 7A is a schematic perspective rear view of one embodiment of africtionless vertical suspension member for use with the prosthetic footmember of FIG. 6A.

FIG. 7B is a schematic perspective side view of the frictionlessvertical suspension member of FIG. 7A.

DETAILED DESCRIPTION OF SOME EXEMPLIFYING EMBODIMENTS

An objective of one or more embodiments described below is to provide alightweight, low energy loss, vertical suspension system for prostheticfeet. The vertical suspension system enables rollover characteristicsbetween heel strike and toe-off that are fit for everyday use and at thesame time encourage highly active users through its suspension, energyreturn and lightness. Additionally, the substantially frictionlessnature of the vertical suspension system results in substantiallygreater energy return than existing suspension systems, and is thereforewell-suited for physically demanding activities such as running.

FIG. 1A shows a conventional prosthetic foot 100. The prosthetic foot100 can have a foot member 15 that extends from a proximal section 13 toa distal section 14. In the illustrated embodiment, the proximal section13 can be generally vertically oriented, and the distal section 14 canbe generally horizontally oriented with the foot member 15 curvingdownward from the proximal section 13 to the distal section 14. Theproximal section 13 can extend to a proximal end 13 a and be generallyat a location of a natural human ankle. In one embodiment, the distalsection 14 can extend to a distal end 14 a generally at a location ofnatural human toes.

With continued reference to FIG. 1A, the foot member 15 can havemultiple elongate segments that can flex independently relative to eachother. In the illustrated embodiment, the foot member 15 has twoelongate segments 16 a, 16 b that are separated from each other by aslot 18 that extends along a length between the distal end 14 a and theproximal end 13 a of the foot member 15. In one embodiment, the slot 18extends along the entire length of the foot member 15. In anotherembodiment, the slot 18 extends along a length that is shorter than theentire length of the foot member 15. In one embodiment, the slot 18extends linearly along its length, so that the width of all the elongatesegments 16 a, 16 b is generally the same.

The prosthetic foot 100 can also have a heel member 45 that extendsbetween a proximal end 43 and a distal end 44 and is disposed below atleast a portion of the foot member 15. In one embodiment, the heelmember 45 can be coupled to the foot member 15 via one or more fasteners50 (e.g., bolts) at a location between the proximal and distal ends 13a, 14 a of the foot member 15 such that the heel member is cantileveredrelative to the foot member 15 and extends to a free rear end at theproximal end 43. The heel member 45 can have a curvilinear profile alongits length that defines an arch 48 between the proximal and distal ends43, 44. The foot and heel members 15, 45 can define a slot 52therebetween in the fore-aft direction at a rear portion of theprosthetic foot 100. In one embodiment, the slot 52 can taper toward afront end of the prosthetic foot 100. A resilient member (not shown) canbe interposed between the heel member 45 and the foot member 15 withinthe slot 52. In one embodiment, the resilient member can separate atleast a portion of the foot member 15 from the heel member 45. Inanother embodiment, the resilient member can completely separate thefoot member 15 from the heel member 45.

In one embodiment, the foot and heel members 15, 45 are plate-likemembers with generally planar top and bottom surfaces and generallyrectangular transverse cross-sections. The foot and heel members 15, 45can be made of lightweight resilient materials, such as graphite,fiberglass, carbon fiber and the like. In some embodiments, the foot andheel members 15, 45 can be formed of multiple layers of material thatdefine a monolithic piece.

FIG. 1B shows an example of a prosthetic foot 200 including a shockmember 201 operatively coupled to the proximal section 213 of the footmember 215. In the illustrated embodiment, the shock module 201 extendsgenerally vertically and includes an attachment clamp 202. The shockmodule 201 can couple to the foot member 215 via one or more fasteners(e.g., threaded fasteners), as further described below. In anotherembodiment, the vertical suspension module 201 can couple to the footmember 215 with an adhesive (e.g., glue, epoxy). In still anotherembodiment, for example as shown in FIG. 1B, the attachment clamp 202 ofthe vertical suspension module 201 can have a recess that receives atleast a portion of the proximal section 213 of the foot member 215therein. The shock module 201 can include an inner pylon and outerpylon. The shock module 201 can further include a resilient element, forexample, a compressible coil spring and/or a compressible fluid coupledto or fixed with respect to the inner pylon. In use, the resilientelement can provide for vertical shock absorption and energy return.

In one embodiment, the prosthetic foot 100, 200 can be coupled (e.g.,removably coupled) to a cosmesis foot cover (not shown) that has anupper portion and a sole portion. In one embodiment, the sole portioncan have an insole with a convex surface that corresponds to thecurvature of a concave bottom surface 48 a of the arch 48 of the heelmember 45, such that the insole maintains contact with the bottomsurface 48 a of the heel member 45 during ambulation of the prostheticfoot 100, 200 from heel strike to toe-off

Further details on prosthetic feet can be found in U.S. Publication2005/0038524, U.S. Pat. No. 7,846,213, U.S. application Ser. No.13/034,474, filed Feb. 24, 2011 and titled “Prosthetic Foot with aCurved Split,” and U.S. application Ser. No. 13/149,118, filed May 31,2011 and titled “Height-adjustable Threaded Shock Absorbing Module andAssociated Coupling Member,” the entire contents of all of which arehereby incorporated by reference and should be considered a part of thisspecification. Further details of foot covers and insole portions can befound in US Publication 2010/0004757 titled “Smooth Rollover Insole forProsthetic Foot” and US Publication 2006/0015192 titled “Functional FootCover,” the entire contents of all of which are hereby incorporated byreference and should be considered a part of this specification.

FIGS. 2-5 illustrate example embodiments of a vertical suspension member1 attached to the prosthetic foot member 15. The vertical suspensionmember 1 can provide certain benefits over other suspension systems,such as the shock module 201 shown in FIG. 1B. For example, the verticalsuspension member 1 can be lighter in weight than other suspensionsystems and can be more dynamic as a result of less friction created inthe vertical suspension member 1 compared to other suspension systems.The vertical suspension member 1 can include a first member 11 and asecond member 12. The first member 11 can be attached to a person'sbody, for example, attached to a person's leg below the person's knee.For example, a socket-style stump attachment system can be provided thatattaches to a stump of the person's residual limb. The stump attachmentsystem can include a socket at one end and a metal rod (e.g.,approximately 25.5 mm in diameter) at the other end. The metal rod canbe removably received into a cylindrical cavity 17 (see FIG. 3) in thefirst member 11. For example, the metal rod may screw into thecylindrical cavity 17 or screws may secure the metal rod inside thecylindrical cavity 17. In another embodiment, a male pyramid connector(not shown) can be inserted into the cavity 17 and threadably coupled tothe first member 11, and a user's stump can be coupled to the pyramidconnector (e.g., via a pylon member).

The second member 12 can be coupled to the foot member 15. In someembodiments, the second member 12 is rigidly or fixedly coupled to thefoot member 15 (e.g., via one or more fasteners (e.g., threadedfasteners), an adhesive (e.g., glue, epoxy), and/or a press-fitconnection between the second member 12 and the foot member 15). Withreference to FIG. 2, the second member 12 can have a recess (not shown)in to which the proximal section 13 of the prosthetic foot 100 can beinserted.

The first member 11 is movably coupled to the second member 12 throughleaf springs 20. Each leaf spring 20 includes a first end 21 and asecond end 22 and is generally plate-like (e.g., planar). As shown inFIG. 2, in one embodiment, the leaf springs 20 are generally rectangularand can readily flex in the longitudinal direction of the springs 20,but not in the transverse direction (e.g., along the width) of thesprings 20. The first end 21 is the end of the leaf spring 20 nearest tothe first member 11. The second end 22 is the end of the leaf spring 20nearest to the second member 12. In one embodiment, the first end 21 canbe rotationally fixed relative to the first member 11 and the second end22 can be rotationally fixed relative to the second member 12. The leafspring 20 is flexible such that applying a downward vertical force onthe first member 11 and pressing the first member 11 towards the footmember 15 will cause the first member 11 to move relative to the secondmember 12. This relative movement between the first member 11 and thesecond member 12 enables vertical suspension between the person's legand the foot member 15. As discussed in greater detail herein, thestiffness and suspension characteristics of the vertical suspensionmember 1 can be customized for individual users by varying, for example,the stiffness, length, and/or number of leaf springs 20 in the verticalsuspension member 1.

In one embodiment, the second member 12 is located between the ankleregion and the thigh region. In another embodiment, the second member 12is flexibly and/or movably coupled to the foot member 15. In yet anotherembodiment, for example the embodiment illustrated in FIGS. 6A and 6B,the second member 12 is integrated into the foot member 15. As shown inFIG. 6C, the foot member 15 includes a longitudinal recess 19 in theproximal section 13. In some embodiment, the recess 19 extends to theproximal end 13 a of the foot member 15. The recess 19 defines two sidewalls 19 a and is designed to receive (e.g., slidably receive) thesecond member 12, for example from a rear of the proximal section 13(e.g., in a posterior-anterior direction) or from the proximal end 13 a(e.g., in a vertical direction). The second member 12 is sized andshaped to slide or otherwise fit into the recess 19. The second member12 can include a flange 40 sized and shaped to abut the rear surface ofthe foot member 15 and side walls 42 sized and shaped to extend into therecess 19 and abut the side walls 19 a of the recess 19. In someembodiments, the second member 12 is secured to the foot member 15 via apress fit, an adhesive (e.g., glue, epoxy), or via any other suitablemechanisms. In another embodiment, a single part may include both thesecond member 12 and the proximal section 13 of the foot member 15, sothat the second member 12 and the proximal section 13 of the foot member15 are monolithic.

In at least some embodiments, e.g., those shown in FIGS. 2-5, thevertical suspension member 1 is an adapter that connects to a prostheticfoot or leg. The adapter can include the first member 11 and the leafsprings 20. The adapter may connect to a coupling device such as thesecond member 12 or the adapter may connect directly to a prostheticfoot and/or leg (e.g., couple directly to the proximal section 13 of theprosthetic foot 100).

In various embodiments, one or more leaf springs 20 couple the firstmember 11 to the second member 12. In some embodiments, the leaf springs20 extend generally horizontally relative to a plane parallel to aground surface between the first member 11 and second member 12 when thefoot is at rest. In some embodiments, for example as shown in FIGS. 2-5,the leaf springs 20 extend from the second member 12 to the first member11 at an angle with respect to a plane parallel to the ground surface.In some embodiments, the leaf springs 20 can be oriented at an angle ofbetween about +/−20 degrees of being parallel to the ground. In someembodiments, the leaf springs 20 can be oriented at an angle of betweenabout +/−30 degrees of being parallel to the ground. In someembodiments, the leaf springs 20 can be oriented at an angle of betweenabout +/−45 degrees of being parallel to the ground. These are onlysample angles and others are possible.

The leaf springs 20 can be rotationally fixed or pivotally attached toone or both of the first 11 and second 12 members. Rotationally fixedleaf spring portions cannot pivot relative to the member to which theyare attached. Pivotally attached leaf spring portions can pivot relativeto the member to which they are attached. In one embodiment, a pivotallyattached leaf spring end can rotate approximately 10 degrees relative tothe member to which it is attached. In one embodiment, at least aportion of at least one leaf spring 20 is rotationally fixed to thefirst member 11 and/or to the second member 12. In another embodiment,at least a portion of each leaf spring 20 is rotationally fixed to thefirst member 11 while at least a portion of each leaf spring 20 isattached to the second member 12 via a pivot such that at least aportion of each leaf spring 20 is able to rotate relative to the secondmember 12. In yet another embodiment, at least a portion of each leafspring 20 is rotationally fixed to the second member 12 while at least aportion of each leaf spring 20 is attached to the first member 11 via apivot such that at least a portion of each leaf spring 20 is able torotate relative to the first member 11. For example, in the embodimentillustrated in FIGS. 7A and 7B, the leaf springs 20 are rotationallyfixed to the second member 12 and coupled to the first member 11 viarolling pins 27. Such an arrangement can advantageously allow forrotation of the first member 11 if an upper stack 25 of leaf springs isoriented non-parallel to a lower stack 26 of leaf springs, as discussedin greater detail herein.

Leaf springs 20 may be secured to the first member 11 and/or to thesecond member 12 via welding, an interference fit, a snap fit,interlocking geometry, adhesives, and/or fasteners (e.g., screws). Forexample, a screw may pass through a hole in the end of the leaf spring20 and through the first member 11 or through the second member 12 tosecure the leaf spring 20 thereto. Leaf springs 20 may be attached tothe first member 11 and/or to the second member 12 via a shackle (notshown), which is a swing arm. In various embodiments, the shackle can beabout 0.75 mm to about 30 mm long between attachment points.

The leaf springs 20 can be flexible to allow the first member 11 to moverelative to the second member 12. The leaf springs 20 can also havesufficient elasticity or resiliency to enable them to approximatelyreturn to their original position after the load that deforms the leafsprings 20 is removed (e.g., during a swing phase in the gait cycle ofthe prosthetic foot). The input force or load is the force between thefirst member 11 and the second member 12 due to the person wearing theprosthetic foot 100 striking or touching the ground. In one embodiment,the first end 21 can move at least 0.75 mm relative to the second end22, compared to a zero input force state, when a force of about 450 Npushes the first member 11 towards the foot member 15 while the footmember 15 is stationary. In another embodiment, the first end 21 returnsto within about 0.75 mm of its starting position when an input force of450 N is removed. In some embodiments, the first end 21 can move betweenabout 5 mm and about 20 mm relative to the second end 22 under appliedloads of between about 500 N to about 3,000 N.

The leaf springs 20 can flex, bend, pivot, and/or arc due to the inputforce or load rather than compress in length such as when a soft pillaris compressed along its axis. In one embodiment, an orientation of theleaf springs 20 can vary over a range of +/−20 degrees relative to aplane parallel to the ground surface as the first member 11 is loadedand unloaded during use. For example, in the embodiment shown in FIG. 2,when the foot member 15 rests on the ground and the first member 11 isunloaded, the leaf springs 20 can be oriented upward toward the front ofthe foot, or at a positive angle with respect to a plane parallel to theground, when viewed from the right side. As the first member 11 isloaded, the first member 11, and with it the first ends 21 of the leafsprings, can move generally vertically downward, causing the leafsprings to flex, bend, pivot, and/or arc so that the leaf springs becomeoriented downward toward the front of the foot, or at a negative anglewith respect to a plane parallel to the ground when viewed from theright side. In another embodiment, the leaf springs 20 can vary over arange of +/−30 degrees relative to a plane parallel to the groundsurface as the first member 11 is loaded and unloaded. In yet anotherembodiment, the leaf springs 20 can vary over a range of +/−45 degreesrelative to a plane parallel to the ground surface as the first member11 is loaded and unloaded. These are example angles, however, and othersare possible.

Various embodiments include diverse leaf spring 20 materials. In oneembodiment, the material of the leaf springs 20 can be hardened steel.In another embodiment, the material of the leaf springs 20 can betitanium. In yet another embodiment, the leaf springs 20 can be madefrom a composite material (e.g., carbon composite) with sufficientelasticity, resiliency and rigidity for the weight and physical activityof the person wearing the prosthesis. Example composite materialsinclude unidirectional glass and/or carbon filaments or fibers in anepoxy matrix. In other embodiments, the leaf springs 20 can be made offiber reinforced plastic or a mixture of graphite and epoxy. Differentmaterials can produce leaf springs 20 having different stiffnesses.

The first member 11 and the second member 12 may be manufactured bymilling stainless steel. In some embodiments, the first member 11 andsecond member 12 are made of aluminum. As noted above, the foot member15 may comprise carbon fiber. In one embodiment, the foot member 15 ismanufactured by combining carbon fibers with plastic resin.

The leaf springs 20 may have uniform cross-sectional geometries or theymay have non-uniform cross-sectional geometries. In one embodiment, theleaf springs 20 have a length and width that makes them rectangular. Inone embodiment, the leaf springs 20 can have a thickness that is lessthan 50% of the leaf springs' 20 length and width. In the embodimentshown in FIG. 2, each leaf spring 20 has a thickness that is less than15% of the leaf spring's 20 length and width. The leaf springs 20 canalso be flat springs or cantilever springs.

In another embodiment, the leaf springs 20 can be trapezoidal cantileversprings. The trapezoidal cantilever springs can have non-uniformcross-sectional geometries. In one embodiment, the leaf springs 20 canhave non-uniform thicknesses along their lengths. For example, the leafsprings 20 may be thicker near the first member 11 than near the secondmember 12. In another embodiment, the leaf springs 20 can havenon-uniform widths. For example, each leaf spring 20 may be 20 mm wideat the first end 21 and 30 mm wide at the second end 22. In someembodiments, the leaf springs 20 may be flat or curved.

In some embodiments, the first 11 and second 12 members can be coupledby two sets of leaf springs, an upper stack 25 and a lower stack 26. Forexample, the embodiments shown in FIGS. 2-5 include 14 leaf springs 20.The leaf springs 20 are divided into two groups of 7. An upper stack 25comprises 7 leaf springs 20 and a lower stack 26 comprises 7 leafsprings 20. As shown, in some embodiments, when the foot member 15 restson the ground and the first member 11 is unloaded, the first member 11,second member 12, upper stack 25 of leaf springs, and lower stack 26 ofleaf springs can be arranged so as to generally form a parallelogramoriented upward toward the front of the foot when viewed from the rightside. As the first member 11 is loaded, the first member 11, and with itthe first ends 21 of the leaf springs, can move generally verticallydownward, causing the leaf springs to flex, bend, pivot, and/or arc.Although the first member 11, second member 12, upper stack 25 of leafsprings, and lower stack 26 of leaf springs can generally retain aparallelogram shape when loaded, the downward movement of the firstmember 11 causes the parallelogram to shift to being oriented downwardtoward the front of the foot when viewed from the right side. In otherembodiments, each stack comprises between 1 and 1,000 leaf springs 20.For example, the embodiment shown in FIGS. 7A and 7B includes an upperstack 25 having 5 leaf springs 20 and a lower stack 26 having 5 leafsprings 20. Varying the number of leaf springs 20 can allow forvariations in overall stiffness of the suspension member 1. In oneembodiment, each leaf spring 20 consists of multiple layers. In theillustrated embodiment, the leaf springs 20 are generally parallel toeach other. In another embodiment, the leaf springs 20 can be within 10degrees of being parallel to each other. As mentioned above, FIGS. 7Aand 7B illustrate an embodiment in which the upper stack 25 of leafsprings 20 is non-parallel to the lower stack 26 of leaf springs. Such anon-parallel configuration can allow for different movements of thevarious components of the vertical suspension member 1 relative to oneanother. For example, when loaded, the first member 11 can pivot in ananterior-posterior plane off vertical as it moves down. A non-parallelarrangement can also result in leaf springs of different lengths, whichcan alter stiffness properties of the leaf springs and verticalsuspension member 1.

FIGS. 2-5 illustrate embodiments wherein the leaf springs 20 in theupper stack 25 do not touch each other and the leaf springs 20 in thelower stack 26 do not touch each other. Leaf springs 20 that do nottouch other leaf springs 20 in the region of the leaf springs 20 thatbend are called independently flexing leaf springs. One advantage ofthis arrangement is that the leaf springs 20 do not create friction byrubbing together, thereby inhibiting energy loss in the verticalsuspension member 1 during use of the prosthetic foot 100. The leafsprings 20 can flex to store the input energy as potential energy. Theleaf springs 20 can then release said potential energy to the user whenthey return to their zero input force position (e.g., to propel theprosthetic foot into toe-off during ambulation).

In another embodiment, leaf springs 20 can rub against each other andthe friction created by rubbing of the springs can dampen movementbetween the first member 11 and the second member 12. This damping canreduce vibrations and/or oscillations between the first member 11 andthe second member 12.

In the illustrated embodiments, the leaf springs 20 are arranged so thatthe first 21 and second 22 ends of each leaf spring 20 are generallyhorizontal. However, in some embodiments, the first 21 and/or second 22ends of one or more leaf springs 20 can be arranged generally nothorizontally, e.g., tilted in the coronal plane. Such an arrangement canadvantageously provide stiffer suspension and/or allow for inversionand/or eversion of the foot during use.

FIGS. 3-5 show a variable stiffness embodiment of the verticalsuspension member 1. This embodiment includes an adjustable leaf spring30. The adjustable leaf spring 30 can be fixed on one end. The other endof the adjustable leaf spring 30 can be grabbed, secured, clasped,and/or captured.

A pivot 34 can fix (e.g., grab, secure) the adjustable leaf spring 30 tothe first member 11. The adjustable leaf spring 30 can be fixed to thesecond member 12 by a clamp 35. When the clamp 35 is open, theadjustable leaf spring 30 is free to slide in and out of the clamp 35(e.g., can be adjusted by a user). When the clamp 35 is closed, theadjustable leaf spring 30 is not free to slide in and out of the clamp35.

Sliding more of the adjustable leaf spring 30 into the region betweenthe pivot 34 and the clamp 35 increases the length of the adjustableleaf spring 30 between the pivot 34 and the clamp 35. Altering thelength of the adjustable leaf spring 30 between the pivot 34 and theclamp 35 influences the stiffness of the vertical suspension member 1.For example, reducing the length of the adjustable leaf spring 30between the pivot 34 and the clamp 35 increases the stiffness of theprosthesis.

When the clamp 35 is open, a person such as a physician, prosthetictechnician, or prosthetic owner can adjust the adjustable leaf spring 30by altering the length of the adjustable leaf spring 30 that is capturedbetween the pivot 34 and the clamp 35. Once the adjustable leaf spring30 is in the desired position, a person can close the clamp 35 to securethe adjustable leaf spring 30. The person can try various lengths todetermine which length results in the desired stiffness.

Although many methods of use are possible, one method includes flexingleaf springs 20 which are part of a prosthesis by applying weight to aprosthetic foot. Another method includes attaching a human leg to aprosthetic foot, such as the prosthetic foot 100, applying weight to aprosthetic foot by walking, and flexing leaf springs 20 that couple thefirst member 11 to the second member 12.

Although the invention is described above with respect to prostheticfeet, the invention can be used with other parts of the body, including,for example, in a full-leg prosthesis wherein the suspension system islocated in the thigh or knee regions (e.g., in a location above theknee). Additionally, one or ordinary skill in the art will recognizethat the use of a vertical suspension member having the featuresdescribed above (e.g., leaf springs) is not limited to prosthetics andcan be incorporate in other applications to provide relativelylightweight vertical suspension with reduced friction.

Of course, the foregoing description is that of certain features,aspects and advantages of the present invention, to which variouschanges and modifications can be made without departing from the spiritand scope of the present invention. Moreover, the vertical suspensionmember need not feature all of the objects, advantages, features andaspects discussed above. Thus, for example, those skill in the art willrecognize that the invention can be embodied or carried out in a mannerthat achieves or optimizes one advantage or a group of advantages astaught herein without necessarily achieving other objects or advantagesas may be taught or suggested herein. In addition, while a number ofvariations of the invention have been shown and described in detail,other modifications and methods of use, which are within the scope ofthis invention, will be readily apparent to those of skill in the artbased upon this disclosure. It is contemplated that various combinationsor subcombinations of the specific features and aspects between andamong the different embodiments may be made and still fall within thescope of the invention, and that the invention has applicability invertical suspension in general, and is not limited to prosthetics.Accordingly, it should be understood that various features and aspectsof the disclosed embodiments can be combined with or substituted for oneanother in order to form varying modes of the discussed verticalsuspension member.

What is claimed is:
 1. A vertical suspension system, comprising: a firstmember having a generally vertically extending longitudinal axis whenthe vertical suspension system is in use and unloaded; a second memberhorizontally spaced from and disposed across from the first member, thefirst member being movable relative to the second member; and aplurality of leaf springs extending between and attached to the firstmember and the second member, the second member comprising a pluralityof slots, each slot configured to receive one of the plurality of leafsprings, the plurality of leaf springs comprising a first stack havingat least two leaf springs and a second stack having at least two leafsprings, the first and second stacks separated by a first distance atone end of the leaf springs, distances between adjacent leaf springs ofthe at least two leaf springs of the first stack at the one end of theleaf springs being smaller than the first distance, the first stackbeing generally vertically above the second stack when in use, whereinthe at least two leaf springs of the first stack of leaf springs arevertically spaced apart from and generally parallel to each other, andthe at least two leaf springs of the second stack of leaf springs arevertically spaced apart from and generally parallel to each other, andwherein, when the vertical suspension system is in use and unloaded, thesecond member has a generally vertically extending longitudinal axisgenerally parallel to the generally vertically extending longitudinalaxis of the first member and the plurality of leaf springs extendgenerally transversely to the generally vertically extendinglongitudinal axes of the first and second members, the generallyvertically extending longitudinal axis of the first member beinghorizontally spaced from and disposed across from the generallyvertically extending longitudinal axis of the second member.
 2. Thevertical suspension system of claim 1, wherein at least one end of theone or more leaf springs is rotationally fixed to at least one of thefirst member and the second member.
 3. The vertical suspension system ofclaim 1, wherein the first stack of leaf springs comprises a pluralityof planar leaf springs that are spaced apart from each other and extendgenerally horizontally between the first member and the second memberwhen the vertical suspension system is in an unloaded state.
 4. Thevertical suspension system of claim 1, wherein the second stack of leafsprings comprises a plurality of planar leaf springs that are spacedapart from each other and extend generally horizontally between thefirst member and the second member when the vertical suspension systemis in an unloaded state.
 5. The vertical suspension system of claim 1,wherein the first member comprises a cavity configured to receive a rodcoupled to a socket configured to be coupled to an amputee's residualleg.
 6. The vertical suspension system of claim 1, further comprising anadjustable leaf spring coupled to and extending between the first memberand the second member.
 7. The vertical suspension system of claim 6,further comprising a clamp configured to couple the adjustable leafspring to the second member.
 8. The vertical suspension system of claim6, further comprising a pivot configured to couple the adjustable leafspring to the first member.
 9. The vertical suspension system of claim1, wherein the first stack of leaf springs is within plus or minus 10degrees of being parallel to the second stack of leaf springs.
 10. Thevertical suspension system of claim 1, wherein the at least two leafsprings of the first stack of leaf springs are vertically spaced apartfrom and generally parallel to each other along their entire lengths,and the at least two leaf springs of the second stack of leaf springsare vertically spaced apart from and generally parallel to each otheralong their entire lengths.
 11. The vertical suspension system of claim1, wherein the first member comprises a plurality of slots, each slotconfigured to receive one of the plurality of leaf springs.
 12. Thevertical suspension system of claim 11, wherein the plurality of leafsprings are coupled to the first and second members solely by theplurality of slots on the first member and the plurality of slots on thesecond member.
 13. A prosthetic foot, comprising: a foot memberextending from a generally vertical proximal portion to a generallyhorizontal distal portion, the foot member curving downwardly andforwardly between the proximal and distal portions; and a verticalsuspension system comprising: a first member disposed forwardly of saidproximal portion toward a distal end of the foot, the first member ofthe vertical suspension system operably coupleable to a prostheticsocket, a second member, wherein the generally vertical proximal portioncomprises a recess configured to receive the second member of thevertical suspension system; and a plurality of leaf springs configuredto operably interconnect and to extend between the first and secondmembers of the vertical suspension system when the prosthetic foot is atrest, each of the plurality of leaf springs having proximal and distalends, wherein each distal end extends to the first member and eachproximal end extends to the second member.
 14. The prosthetic foot ofclaim 13, wherein the recess extends to a proximal end of the footmember.
 15. The prosthetic foot of claim 13, wherein the second membercomprises a flange sized and shaped to abut a rear surface of the footmember.
 16. The prosthetic foot of claim 13, wherein the leaf springsare spaced apart from and generally parallel to each other.
 17. Theprosthetic foot of claim 13, wherein the plurality of leaf springscomprises an upper set of leaf springs and a lower set of leaf springs,wherein the upper stack of leaf springs is non-parallel to the lowerstack of leaf springs.
 18. The prosthetic foot of claim 17, wherein thelower set of leaf springs extends generally horizontally and the upperset of leaf springs extends at an angle between the first and secondmembers.
 19. The prosthetic foot of claim 13, wherein the second memberand the proximal portion of the foot member are monolithic.
 20. Theprosthetic foot of claim 13, wherein the second member is secured to thefoot member via a press fit.
 21. The prosthetic foot of claim 13,wherein the second member is secured to the foot member via an adhesive.